..
role My::Config::ConfigEmail {
    has attr_valid_domain => (
        isa => 'Str',
        is => 'rw',
        required => 1,
    );
    method parse($instance!, $value!) {
        ..
        $instance
            ->meta
            ->find_attribute_by_name($self->attr_valid_domain)
            ->get_value($instance);
        ..
    }
    ..
}